Hi Don (and all who have offered advice & help) Thanks to all for the input that has been offered. Based on some of the comments, I thought I might share the 'rest of the story', both to seek additional input, and to show the technical trade off's associated with a compromise antenna environment.
I'm installing a used HF-6v in a CCR environment, so I have some environment limitations. The CCR 'enforcement' committee is not horribly aggressive, but if I don't aggravate the situation, I'm much better off. I have a 24' tree, with some 3-4' bushes at the base, in a desert/rock landscaped front yard. The back has no 'cover' yet, and antenna's are more visible in spite of a fence. The plan is to install the antenna obscured by the tree, in the front yard. Given the landscaping, ground mounted with a full radial system is not possible so elevating the antenna as high as possible without guys or objectionable visibility wash chosen. My last HF-6V had 32 ea 32' buried radials, wish I could reproduce that ! So, the HF6 will be mounted about 4' off the ground, a full elevated radial system is not possible. Choices seem to be the CPK solution from Butternut or a modified radial system. Two options are being considered on the modified radials. First, 3 tuned radials (either individual wires for 40/15, 30, 20, 15,10 or the Butternut tuned twinlead variety) could be connected at the base of the antenna, then run down (hidden in the bushes) at a 60 degree angle to ground level, then run under/around the rocks. Performance is expected to be better than the CPK, but still a compromise. Routing is not linear. Tuning of this radial environment is expected to be a bear ! The second, the CPK, is expected to be enhanced by the low elevation, but NOT as effective as a good ground radial system. I might be able to enhance this configuration by laying out a psuedo radial set of 6-10 8' wires at the base of the 4' mast, which would more accurately be a surface capacitive element to enhance the CPK's effect. In neither case will the near field ground losses be impacted. There are some spiral wound counterpoise idea's out on the web, as well as some thoughts on constant angle spirals, which are tempting, but at this juncture, I expect to lean to the CPK to get it up and running, with spirals and experiments to follow... So any additional input, idea's, are solicited and welcome Thanks again all, Niel Don Wilhelm wrote: > Remember (or understand if you did not before) that elevated radials > should be tuned (pruned for length) just like a part of the antenna > (they *are* part of the antenna). > > So get out your antenna analyzer and cut one radial a bit on the long > side - attach only that one radial to the vertical and shorten it until > you have the correct readings on the antenna analyzer. Cut the second > radial to the same length - move to the next band and do the same thing > until you are done. Note that the radials can interact on a multiband > setup (just like parallel dipoles), so tune the lowest bands first and > move upward in frequency one band at a time. > > The twinlead solution does work, but suffers badly from interaction. > > 73, > Don W3FPR > > Jerry Flanders wrote: >> At 04:54 PM 8/19/2008, Vic K2VCO wrote: >>> >>> You don't need an expensive 'kit'! Just take any old wire and make >>> two 1/4 wavelength radials for each band -- a total of 12 radials. >>> Try to make them as symmetrical as possible, with the two 40 meter >>> radials opposite each other, etc. >>> >>> The ends of the radials must be well-insulated, since even though >>> they are connected to the coax braid at the center, they will develop >>> high-ish voltages at the ends. >>> -- >>> 73, >>> Vic, K2VCO >> >> Details on making a multiband radial from twin-lead are at: >> http://www.bencher.com/pdfs/00366IZV.pdf >> >> Jerry W4UK _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
